Radio frequency coupling devices



July 17, 1956 F. ENGELMANN 2,755,447

RADIO FREQUENCY COUPLING DEVICES Filed 001.29, 1954 5 Sheets-Sheet 2 ATTORNEY July 17, 1956 F. ENGELMANN 2,755,447

RADIO FREQUENCY COUPLING DEVICES Filed Oct. 29. 1954 3 Sheets-Sheet 3 ATTORN Y RADIO FREQUENCY COUPLING DEVICES Herbert F. Engelmann, Mountain Lakes, N. 1., assignor to International Telephone and Telegraph Corporation, Nutley, N. J., a corporation of Maryland Application October 29, 1954, Serial No. 465,628

'12 Claims. (Cl. 333-24) This invention relates to radio frequency coupling devices and more particularly to a Waveguide coupling section employing a gyratory element through which radio frequency energy is freely transmitted in one direction but which is prohibited in the opposite direction.

Such one-way gyratory coupling devices have been roposed heretofore but in such instances the waveguide plumbing utilized including the arrangement of the gyratory element and associated equipment for producing the necessary magnetic field are bulky, complicated and extremely expensive. An obiect of the present invention, therefore, is to provide an improved one-way gyratory coupling device for radio frequency energy Which is relatively simple and easy to build and which is relatively inexpensive.

An important feature of this invention is the fact that the coupling device can be made, for the most part, by printed circuit technique. The parts capable of being printed include the waveguide input and output connections as well as the transducer portions which co-act with the gyratory element to effect one-way transmission. The waveguide structure, in one embodiment, is made in accordance with the microstrip principle which includes two strip-like conductors disposed in dielectrically spaced parallel relation with one of the strips wider than the other to present thereto a planar conducting surface for propagation of wave energy therealong in a mode approximating the TEM mode. The electric field in such propagation is distributed in a manner similar to the electric field distribution between one conductor and the neutral plane of a truly parallel two conductor line. The narrower of the two strips is continued beyond the other and printed in the form of a fiat spiral which effects a translation of wave energy from linear polarization to circular polarization. For further details of such transducers, reference is had to my copending application Serial No. 349,118, filed April 16, 1953, for Phase Shifter. In other embodiments the Waveguide may comprise either a printed sandwich line or a dielectric filled coaxial line wherein the inner conductor is coupled to the spiral. A body of material including ferrites is disposed between the two fiat spirals of the input and output sections and means are provided to impress a magnetic field on the body of ferrite material in a direction axially of the two spirals. By impressing a magnetic field of sufiicient strength a gyro-resonant condition is produced in the body of ferriies corresponding to the aterrt The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a view in plan of a coupling device according to the principles of this invention;

Fig. 2 is a cross-sectional view taken along lines 2-2 of Fig. 1;

Fig. 3 is a view in plan of the upper spiral section as viewed along lines 3-3 of Fig. 2;

Fig. 4 is a view in plan of the ferrite body;

Fig. 5 is a view in plan of the bottom spiral section as viewed along lines 5-5 of Fig. 2;

Fig. 6 is a vertical cross-sectional view of another embodiment of the invention;

Fig. 7 is a view in plan of the device shown in Fig. 6; and

Fig. 8 is a cross-sectional view taken along lines 8-8 of Fig. 6.

Referring to the drawings, the input waveguide is shown to include a first or planar conductor l, a second or strip conductor 2, and a layer of dielectric material 3 which separates the conductors 1 and 2 in parallel relation. The dielectric material may comprise polyethylene, polystyrene, Teflon, fiber glass or laminations of fiber glass and Teflon or other suitable material of dielectric quality, or if the waveguide structure permits, the dielectric may be air. The output waveguide is of corresponding construction and includes a first or planar conductor 1a, a second or strip conductor 2a and a layer of dielectric material 3a. The planar conductors 1 and 1a are terminated in a short cylindrical housing 4 one end of which is closed by an extension 7 of the layer of dielectric material 3 while the other end is closed by an extension 8 of the layer 3a. The conductor strip 2 is also extended in overlying relation to extension 7 and is connected by a rivet or other suitable connecting means 9 to a spiral conductor 5 on the opposite side of the dielectric layer. The conductor 2a is connected in a similar manner to a spiral conductor 6 by connection 9a through the dielectric extension 8. The two spirals 5 and 6 are of the same rotational sense and are disposed in axial alignment with a gyratory element 10 interposed therebetween. The element It} includes polyirons and ferrites, the latter having the general formula ROFezOs in which R stands for a bivalent metal ion. The ferrites are those containing bivalent ions of magnesium, zinc, copper, nickel, iron, cobalt, manganese, or mixtures thereof.

Disposed with the north and south poles 11 and 12 in axial alignment with the spirals 5 and 6 is an electromagnetic device 13 having a coil 14 and means 15 for controlling the strength of magnetic field. In operation the magnetic field impressed across the body 10 is selected so as to produce a gyro-resonant effect in the body. The spiral 5 is arranged so that the conductor thereof is of a length to produce resonance at the operating frequency and the curvature thereof is such that the electric fields at two points spaced apart along the spiral conductor are in quadrature. The spiral 5 launches the wave energy with circular polarization in a directional sense compatible to the directional rotation of gyro-resonance in the body 10. The input Wave energy is accordingly passed practically lossless by the body 10 and is picked up by the spiral 6 which corresponds in rotational sense to spiral 5 and translates the circular polarized wave to linear polarization for propagation along the output waveguide structure. Any wave energy flowing in the reverse direction over the output connection B is launched by spiral 6 in a circular polarization having a rotational sense opposite to that of the input wave energy launched by spiral 5. In view of this opposed relationship the wave energy launched in the reverse direction by spiral 6 is completely absorbed in the body 10 thereby insuring a uni-lateral direction of propagation through the coupling device.

In the manufacture of the coupling device according to my invention the size and configuration of the conductors 2, 2a, 5 and 6 are predetermined and covered with a suitable acid resist material. The portions of the conductors 1 and 1a to be retained are also covered with the acid resist material. By known etching process the unwanted portions of the conductive layers are removed leaving the desired configurations of the conductors. This operation obviously can be repeated accurately for production purposes. The tubular wall 4 is connected as by soldering to the conductors 1 and 1a, and may include a flange 4a to overlap the strip extensions 7 and 8. This housing is desirable for the purpose of enclosing the coupling device and also to effect shielding against loss due to radiation.

In Figs. 6, 7, and 8, a second embodiment is shown which is completely shielded. The unit comprises an input waveguide 16 and an output waveguide 17 coupled together by a cylindrical housing 13. Each of the waveguides is in the form of a coaxial line preferably of the rectangular form comprising an outer conductor 19 and an inner conductor 20. The inner conductor 20 is shown to be of flat strip form and supported by solid dielectric 21 which fills the outer conductor 19. It will be understood, of course, that the coaxial line may be an air line in which case the center conductor 20 is provided with spacers at points therealong, and as an alternative the waveguide may be of the sandwich type comprising only the upper and lower parallel walls with the center conductor sandwiched therebetween. In either case, the center conductor is terminated centrally of the housing 18 and provided with a spiral portion 22 to effect circular polarization of the wave energy. The two spiral portions 22 and 23 are disposed in axial and parallel spaced relation and the spirals are in the same rotation sense so that when a magnetic field is applied between the north and south poles 24 and 25 wave propagation will pass through the ferrite body 26 in one direction and be inhibited in the opposite direction. The outer conductor 19 of each of the waveguides is connected to the housing 18 so that the housing completely shields the spirals 22 and 23 and the ferrite body 26. Where the waveguides are of the sandwiched type the inner and outer conductors thereof including the spirals may be formed by printed circuit technique.

Regardless of the type of waveguide connection for the radio frequency coupling device, suitable transducers may be provided for coupling to other types of waveguides. The rectangular waveguide 16, for example, may be coupled directly to a circular coaxial line by means of a gradual reshaping section or to a hollow rectangular waveguide by means of a ridge transducer coupled to the center conductor. The rectangular coaxial waveguide may also be coupled directly to a microstrip waveguide by connecting the center conductor to the line conductor and the outer conductor to the planar or ground conductor of the microstrip waveguide.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by .way of example and not as a limitation to the scope of 'my' invention as set forth in the objects thereof and in the accompanying claims.

I claim:

1. A coupling device for radio frequency energy comprising an input transducer having a conductor in the form of a spiral within a waveguide section to transform linearly polarized waves to circularly polarized waves,

an output transducer having a conductor within said wavegnlide section in the form of a spiral corresponding in rotational sense to the spiral of said input transducer to transform the circularly polarized waves to linearly polarized waves, said spiral conductors being coaxially disposed in spaced relation, a body of material including ferrites disposed between said spiral conductors and means for impressing a magnetic field on said body in the direction of wave propagation to produce a gyroresonant condition in said body.

2. A coupling device for radio frequency energy comprising an input transducer having a conductor in the form of a flat spiral within a waveguide section to transform linearly polarized waves to circularly polarized waves, an output transducer having a conductor within said waveguide section in the form of a flat spiral corresponding in rotational sense to the spiral of said input transducer to transform the circularly polarized Waves to linearly polarized waves, said spiral conductors being coaxially disposed in parallel spaced relation, a body of material including ferrites disposed between said spiral conductors and means for impressing a magnetic field coaxially of said spiral conductors on said body to produce a gyro-resonant condition in said body.

3. A coupling device for radio frequency energy comprising an input transducer having a waveguide section including therewithin a spiral conductor to transform linearly polarized waves to circularly polarized waves, an output transducer including said waveguide section and having a spiral conductor disposed therewithin in the same rotational sense as the input spiral conductor to transform the circularly polarized waves to linearly polarized waves, said spiral conductors being coaxially disposed in spaced relation, a hollow cylindrical conductor disposed concentrically in dielectrically spaced relation about said spiral conductors, a body of material including ferrites disposed between said spiral conductors and means for impressing a magnetic field on said body coaxially of said spiral conductors to produce a gyroresonant condition in said body.

4. A coupling device for radio frequency energy comprising an input waveguide, an output waveguide, each of said waveguides having a first conductor, a second conductor and means disposing said conductors in dielectrically spaced parallel relation, said first conductor being wider than said second conductor to present thereto an extended surface for electrical field distribution of radio frequency waves propagated therealong, the second conductor of each waveguide being terminated in a spiral form to effect circular polarization of the radio frequency energy, a waveguide section surrounding each of said spiral portions and being connected to said first conductors, the spiral portions of said second conductors being axially disposed in spaced relation and in the same rotational sense, a body of material including ferrites disposed between said spiral portions and means to impress a magnetic field on said body axially with respect to said spiral portions.

5. A coupling device for radio frequency energy comprising an input waveguide, an output waveguide, each of said waveguides having a first conductor, a second conductor and a strip of dielectric material disposing said conductors in spaced parallel relation, said first conductor being wider than said second conductor to present thereto an extended surface for electrical field distribution of radio frequency waves propagated therealong, each said strip of dielectric material being extended beyond the end of said first conductor with the second conductor carried on said extended portion being terminated in a planar spiral form to effect circular polarization of the radio frequency energy, a waveguide section connected to each of said first conductors, the spiral portions of said second conductors being axially disposed within said section in parallel spaced relation and in the same rotational sense, a body including ferrite material disposed between said spiral portions and means to impress a magnetic field on said body axially with respect to said spiral portions.

6. A coupling device for radio frequency energy comprising an input waveguide, an output waveguide, each of said waveguides having a first conductor, a second conductor and a strip of dielectric material disposing said conductors in spaced parallel relation, said first conductor being wider than said second conductor to present thereto an extended surface for electrical field distribution of radio frequency waves propagated therealong, each said strip of dielectric material being extended be yond said first conductor and carrying thereon in the plane of said first conductor a spiral conductor mounted within a common waveguide section to effect circular polarization of the radio frequency energy, said section being coupled to each of said first conductors, means coupling each said spiral conductor to the said second conductor on the opposite side of the strip of dielectric material, said spiral conductors being axially disposed in parallel spaced relation and in the same rotational sense, a body including ferrite material disposed between said spiral conductors and means to impress a magnetic field on said body axially with respect to said spiral conductors.

7. A coupling device for radio frequency energy comprising an input waveguide, an output waveguide, each of said waveguides having a first strip conductor, a second strip conductor and a strip of dielectric material disposing said strip conductors in spaced parallel relation, said first strip conductor being wider than said second strip conductor to present thereto a planar surface for electrical field distribution of radio frequency waves propagated therealong in a mode approximating the TEM mode, the second strip conductor of each waveguide being extended in a fiat spiral form beyond the end of the corresponding first strip conductor, the length and curvature of the spiral conductors being such as to be resonant at the operating frequency and to effect circular polarization of the radio frequency energy in the same rotational sense, the spiral portions of said second strip conductors being axially disposed in parallel spaced relation, a hollow cylindrical conductor disposed concentrically in spaced relation about said spiral portions and interconnecting said first conductors, a body including ferrite material disposed between said spiral portions and means to impress a magnetic field on said body axially with respect to said spiral portions.

8. A coupling device for radio frequency energy comprising an input transducer having a conductor in the form of a spiral within a Waveguide section to transform linearly polarized Waves to circularly polarized waves, an output transducer having a conductor in the form of a spiral within said waveguide section corresponding in a rotational sense to the spiral of said input transducer to transform the circularly polarized waves to linearly polarized waves, said spiral conductors being coaxially disposed in spaced relation, a body of material including ferrites disposed between said spiral conductors, a conductive housing enclosing said spirals and said body, said housing having a first opening for said input transducer and a second opening for said output transducer, and means for impressing a magnetic field on said body in the direction of wave propagation to produce a gyro-resonant condition in said body.

9. A coupling device for radio frequency energy comprising an input waveguide, an output waveguide, each of said waveguides comprising a coaxial line having inner and outer conductors, a conductive housing having input and output openings, said input and output coaxial lines being coupled to said housing with the inner conductors thereof extended through said input and output openings, respectively, each of said inner conductors being terminated within said housing in a spiral to effect circular polarization of the radio frequency energy, the spiral portions being axially disposed in spaced relation and in the same rotational sense, a body of material including ferrites disposed between said spiral portions and means to impress a magnetic field on said body axially with respect to said spiral portions.

It). A coupling device for radio frequency energy comprising an input waveguide, an output waveguide, each of said waveguides comprising at least two planar conductors with a center conductor sandwiched in dielectrically spaced relation therebetween, a conductive housing coupled to said input and output waveguides with the center conductors thereof extending into said housing, each of said inner conductors being terminated in a spiral to effect circular polarization of the radio frequency energy, the spirals being axially disposed in spaced relation and in the same rotational sense, a body of material including ferrites disposed between said spirals and means to impress a magnetic field on said body axially with respect to said spirals.

11. In a coupling device for radio frequency energy, an input transducer having a conductor in the form of a fiat spiral within a waveguide section to transform linearly polarized waves to circularly polarized waves, an output transducer having a conductor in the form of a flat spiral within said waveguide section corresponding in rotational sense to the spiral of said input transducer to transform the circularly polarized Waves to linearly polarized waves, said spiral conductors being coaxially disposed in parallel spaced relation, and a body of material including ferrites disposed between said spiral conductors.

12. In a coupling device for radio frequency energy, an input waveguide, an output Waveguide, each of said waveguides having at least a first conductor, a second conductor and a strip of dielectric material disposing said conductors in spaced parallel relation, said first conductor being wider than said second conductor to present thereto an extended surface for electrical field distribution of radio frequency Waves propagated therealong, a cylindrical waveguide section, each said strip of dielectric material being extended beyond the end of said first conductor with the second conductor carried on said extended portion being terminated in a planar spiral form within said section to efiect circular polarization of the radio frequency energy, and the spiral portions of said second conductors being axially disposed in parallel spaced relation and in the same rotational sense.

References Cited in the file of this patent UNITED STATES PATENTS 2,114,031 Rust et al Apr. 12, 1938 

